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“Rapidly Renewable” (or “Bio-Based”) materials
points in green building rating systems are some of the most challenging to
acquire. In the LEED rating system, rapidly renewable is defined as: “Materials
and products [that] are made from plants that are typically harvested within a
10-year or shorter cycle.” The Green Globes rating system uses the term
bio-based and defines the term as: “Commercial or industrial product grown or
harvested utilizing at least 50 percent (by weight) sustainable,
biologically-generated substances, including but not limited to cellulosic
materials (wood, straw, natural fibers) and products made from crops
(soy-based, corn-based).”

LEED offers a single point for using rapidly renewable materials with a minimum
value of 2.5 percent of all materials used in the building. Use of Bio-Based
materials in the Green Globes rating system gives project teams a total of 6
possible points for using anywhere from 1 to 20 percent of materials used in
the building.

The LEED rating system effectively removes any wood-based material or product
from consideration due to the 10 year harvest cycle requirement. Green Globes
recognizes that wood is a renewable resource, and as such should be rewarded
for use in a building even if it isn’t rapidly renewable but must also be
certified as sustainably harvested to contribute. In both cases, it has been
difficult to get the points because so few of the materials used in a building,
as a percentage of cost, are rapidly renewable or bio-based. This may soon
change because new rapidly renewable/bio-based products have been developed and
are now entering the market. In this article, I explore the possibilities of
maximizing the potential to acquire these points using a building currently in
design at architecture firm I work for.

Squeezing Rapidly Renewable, Bio-Based Materials into a Building

The building I am currently working on is a
college campus administrative office facility approximately 60,000 square feet
with an estimated construction budget of $23 million. The building is being
designed to achieve a LEED Platinum rating, with nearly all available points
being pursued, including MR Credit 6 - Rapidly Renewable Materials. The first
step in tacking this credit is to calculate the required dollar amount needed
to get to the 2.5 percent threshold. LEED allows project teams to use a .45
multiplier to come up with a default materials budget cost, which for this
project is $10.3 million. To calculate the amount needed for MRc6, this number
is multiplied by 2.5 percent, which equals $258,750. This is the minimum that
rapidly renewable materials must amount to for the award of the
point.

The list of possible materials identified in the LEED rating system reference
guide includes bamboo flooring, cotton batt insulation, linoleum flooring,
sunflower seed board panels wheatboard cabinetry, wool carpeting and cork
flooring. In addition to these materials the project team also found new
products like a phenolic resin laminate-faced composite wall panel made with 30
percent bamboo fiber and an acoustical ceiling panel made with 100 percent
jute.

The team identified several materials early in the planning process that could
be specified toward achievement of this credit, including the following (dollar
amount contribution in parentheses):

All added up, the total comes to $132,500-only half way to the mark! With
roughly an additional $130,000 to go to achieve the point, it has become cost
prohibitive to the project, extremely disappointing considering the teams
deliberate approach in selecting materials toward its achieving. Were Green
Globes being used as the rating system for the project, the materials selected
would have earned the project one of the six available points.

Are Rapidly Renewable, Bio-Based Materials Better for the Environment?

When I served on the LEED Materials and
Resources Technical Advisory Group, many discussions were had concerning the
environmental consequence of favoring rapidly renewable materials over any
other. At that time, information available to the group suggested that not all
bio-based materials were equal. Bio-based materials originate from things grown
and harvested and this process can result in a very large, negative
environmental consequence. Add to this the impacts for processing into
materials and products, in-service use, and end of life disposal and the
footprint gets even bigger.

I was not all that surprised, then, with similar conclusions drawn in a new
study “Sustainability Metrics: Life Cycle Assessment and Green Design in
Polymers,” which appeared in the publication Environmental Science &
Technology, September 2, 2010. The study compares the environmental attributes
of 12 polymers, some bio-based, the rest petroleum-based, using Green Design
Principles and Life Cycle Assessment. The bio-based polymers are highly ranked
using the Green Design Principles due in large part to the fact that the Principles
value bio-based content above all other-no surprise here. The same bio-based
polymers don’t fare so well, however, when evaluated with Life Cycle Assessment
analyses. The study concludes that:

“While biopolymers uniformly rank highly in terms of green design, they exhibit
relatively high environmental impacts from production. As shown through the LCA
results, biopolymers represent decreases in fossil fuel use and global warming
potential and increases in other impact categories such as eutrophication,
human health impacts, and eco-toxicity. These impacts result both from
fertilizer use, pesticide use, and land use change required for agriculture
production as well as from the fermentation and other chemical processing
steps.”

The study is interesting, but not all that useful to building practitioners
because it does not account for any impacts associated with the use or
end-of-life of the materials, significant factors that must be accounted for
with regard to building materials, as emphasized in the study with this
conclusion:

“… the environmental and human health impact of chemical byproducts of
[bio-based] PLA or [bio-based] PHA biodegradation have yet to be studied. The
biodegradation of these polymers inherently produce the greenhouse gases carbon
dioxide and methane.”

Conclusion

More and more rapidly renewable, bio-based building materials are becoming
available and easier to incorporate into buildings. This can make it easier to
achieve green building rating system points, but usually at a price. In the
example given above, if the client had an unlimited budget, the LEED point for
this credit would be easily achievable simply by adding more linoleum, or
bamboo flooring, or even using a more expensive line of linoleum or bio-based
composite wall panel (the range in price per square foot for these materials
can be huge, depending on color, thickness, texture, etc.). Unfortunately, most
clients do not have unlimited budgets which means that, even with an abundance
of rapidly renewable, bio-based materials available, the available point(s)
will remain very expensive to chase.

The very real issue of whether or not maximizing the use of these materials is
really better for the environment at all is something that every project team
should carefully consider. Doing the right thing from an environmental
standpoint does not necessarily include the pursuit of rapidly renewable,
bio-based points.

Chris Dixon is a registered architect, Certified
Construction Specifier, and LEED AP. He serves on GBI’s Green Globes Technical
Committee and is a former USGBC Materials and Resources Technical Advisory
Group member.

Check out the May 2020 edition of Walls & Ceilings: The devoted team of Green Country Drywall at a recent job site in Oklahoma, rainscreen drainage and ventilation mats, SBA loans via the CARES act, and much more!